title: Posterior fossa arachnoid cyst demonstrated by ultrasound.
mesh_terms: D001099:Arachnoid; D003388:Cranial Fossa, Posterior; D003560:Cysts / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D008297:Male; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography